How would you define reality?

Very good question.

Perception. The way your senses interpret your existence in your surroundings

Cops often say 'Stick five observers on a street corner and stage an incident in front of them.
Then go take statements from the witnesses.
You'll get five different interpretations of what just happened.

That's because we all interpret our surroundings and interaction with them differently.

So reality as some sort of 'Flat fact' doesn't apply equally to everything all the time.
And if it involves groups ?
You can bet 'reality' is defined by the majority....whether it be true or not.